Telephone system



1 Jan. 25 1927. v

C. E. LOMAX TELEPHONE SYSTEM Filed March 14, 1923 Clarence E- LumEIX Patented Jan. 25, 1927.

UNITED STATES PATENT OFFICE;

CLARENCE E. LOMAX, OF CHICAGO, ILLINOISjASSIGN'OR, BY MESNE ASSIGNMENTS,TO'

AUTOMATIC ELECTRIC INC, OF CHICAGO, ILLINOIS, A" CORPORATION OF DELA- WARE.

TELEPHONE SYSTEME.

Application filed March 14, 1923 The present invention relates in general to telephone systems, but more particularly to intercommunieating systems in'which each station isprovided with a plurality of keys,

each key being capabieof establishing a con nection between the callingstation and thevision of atalking. link so adapted thatthe operation of a singl'e key will cause the callployed in a system embodying the principles of the invention to enable the same to be understood.

Reterringto the drawing, the stations-#1 and #Sare ordinary telephone stations utilizing a direct current receiver and a common battery transmitter. hen the switch hook is normal, the relays 9 and 10 are in bridge across their respective lines. WVhen a station is called; direct current causes the associated relay to energize andopen its own circuit, the relaytherefore'acting as a buzzer to signal the called subscriber.

The calling finder switch S and the called finder switch S are located at a central point; The finder switches are of the rotary type in which the wipers move in a "forward direction only. The switch controls a set of wipers having access to banks B, B and 13 while theswitch S controls a set of wipors' having access to banks'B B and B The positive and negative talking conductors from each substation in the system terminate-upon contacts in the banks 13 and B respectively. The contacts in bank B are multipled with the contacts in bank B while the contacts in bank B are multiplied with the contacts in bank A plurality ot locking keys are provided ing end of this link to. attach itself to the Serial no. 624,916.-

at each-substation, thGIGlJGlHg-OIIS key foreach telephone'in the system. As show-nin thefigure; thekey set K isassociated wlth substation #1. The key set Y is associated with the second station (not shown), while the key set K is-associated with substation #8. It will beseenthat there are'no' series connections, and that themultipling'ot-key sets may be'carried on as desired.

The start conductor 15 is multipled into every key in the system. There is also a calling multiple, such as the multiple 18, 19, or 20,which is local to each key, set.

The calling multiple from a given key set is connected to that contact in bank B" which:

corresponds to the contacts in banks B and 13, upon which theassociated line conductors are terminated. There is a called multiple, such as the multiple 21, 22, or 23,for each substation in' the system. The cal-led multiple for a given station is looped into a key in each 'key'set, and is connected to that con tact in the bank 13* which corresponds to the contacts in banksB and B to which the associated line conductors are multipled.

In general the operation of the system is as follows: lVhena subscriber desires to call acertain substation he operates the corre* sponding key of his key set. This operation starts the rotation of both switch S and switch S. for a grounded line, while'thecalledswitch S" will seek a line carrying.battery'potential.

The calling: switch S will seek A further result of the operation of the aforementioned key is the grounding of the calling multiple through a resistance. still iurtherresult of the operation of the aforementioned key is the connectionot' the called multiple with the calling multiple. As aresult of the foregoing ground through a resistance will be placed upon a certainv now appears upon a certain contact in the bank B hen-the wipers of the switch S reach thev above mentioned contact in bank B the rotation will cease, and a switching relay will operate.

When the calling switching relay operated, battery was placed upon the calling line, and as a result the relay at the calling substation operates to advise the calling subscriber that the connection has been co1npleted. W hen the called switching relay operated battery was placed upon the called line, and as a result the relay at the called substation operates to signal the called subscriber. The first subscriber to remove his receiver will receive a ring back tone as an indication that the other party has not an swered.

When the conversation is completed, the receivers are replaced, whereupon the relay at the calling substation will again operate as an indication that the operated key must be restored. lVhen the key is restored the system returns to normal and is in readiness to complete another connection.

The system having been described in general, a detailed description will now be given of its operation. For this purpose it will be assumed the subscriber at substation #1 desires to call substation #8. When key 8 of key set K is operated a circuit is closed from ground, working contact and spring 24, starting conductor 15, conductor 25, resting contact and armature 26, armature 2'? and resting contact, relay 28 to battery. A branch of the above circuit extends from grounded starting conductor l5,conductor 29, resting contact and armature 30, armature 31 and its resting contact, relay 32 to battery. Relays 28 and 32 will energize and close the circuits of stepping magnets 33 and 34, respectively. Stepping magnet 33, upon energizing, will open the circuit of relay 28 at armature 27, thus the relay 28 and the stepping magnet 33 will operate alternately to advance the wipers of switch S step by step over the bank contacts. Stepping magnet upon energizing, opens the circuit of relay 32 at armature 31; thus the relay 32 and the stepping magnet 34 will operate alternately to advance the wipers of switch S step by step over the bank contacts.

A further result of the operation of key 8 in key s-ct K is the placing of ground upon the first contact in bank B over a circuittraceable from ground, resistance R, spring 35 and its working contact, calling multiple 20 to the first contact in bank B.

A still further result of the operation of the above mentioned key is the connection of the called multiple 21 with the calling multiple 20 at spring 36. At this time ground tlu'ough resistance R is placed upon the eighth contact in bank 13*, but without effect.

When the wiper 17 engages the grounded contact in bank B a circuit may be traced from ground, resistance R, spring 35 and its working contact, calling conductor 20, first contact in bank B, viper l7, relay 3?, to battery. Relay 3?, upon energizing, stops the rotation of switch S by opening the circuit to relay 28 at armature 2G. sult of the cnergization of relay 3? is the placing of battery potential upon the eighth contact in bank .B-. When the wiper 16 engages this contact a circuit may be traced from ground, relay 38, wiper 16, eighth contact in the bank B called multiple 21, spring 36 and its working contact, spring 35 and its working contact, calling multiple 20, first contact bank B, wiper 17, relay 37, to battery. From the foregoing it will be seen that relay 38 is now in multiple with resistance 1%. Relay 38, upon energizing, stops the rotation of switch 55 by opening the circuit of relay at armature 30.

A further result of the operation of relay 37is the closure of a circuit traceable from ground, lower winding of relay 39, working contact and armature 40, wiper 12, first contact bank 13 positive line, normal switch hook contacts, relay 9, armature 53 and its resting contact, negative line, first contact bank 13 wiper 11, armature 4.1 and its working contact, upper winding relay 39, to battery. The relay 9 will operate as a buzzer to indicate that the connection has been established.

A further result of the cnergization of relay 38 is the closure of a circuit traceable from ground, lower winding relay 50, working contact and armature 52, wiper ll, eighth contact bank 13, positive line, resting contact and armature 54, relay 10, normal switch hook springs, negative line, eighth contact bank 13, wiper 13, armature 51 and its working contact, upper winding relay to battery. Relay 1O accordingly operates as a buzzer to signal the called party at station #8.

When the receivers are removed talking battery will be fed to stations #1 and #8 through impedance coils 39 and 50, respectively, and the conversation will proceed through the talking condensers 55 and 56. The first subscriber to remove his receiver will receive a ringback tone from the buzzer at the other substation as an indication that the other party has not answered.

lVhen the conversation is completed, the receiver will be restored and the relay 9 at the calling substation will operate as an indication that key 8 of key set K must be restored. lVhen key 8 is restored the circuit of relays 37 and 38 is opened, whereupon the said relays deenergize and the system returns to normal.

In further explanation let us assume that a connection has been established from staion #1 to station #8. If at this time the subscriber at substation desires to call substation #8 he will operate key 8 01 key A further reset K whereupon ground will be placed upon the second contact in the bank B.

The eighth contact of bank 13* is now connected through key 8 of key set I to the second contact in bank B. Additional ground has been placed upon start conductor 15, but without effect owing to the open contacts at armatures 26 and 30.

\Vhen the present conversation is completed the receivers will be restored, and key 8 of key set #1 will be restored to normal. The relays 37 and 38 will now deenergize and again close the grounded start conductor 15 through to relays 28 and 32, respectively, whereupon the switch S will advance its wipers into engagement with the second set of contacts in its bank, after which switch S will come to rest with its-wipers'in engagement with the eighth set of contacts in its bank. The calling and called subscribers will now be signalled in the usual manner.

If it should happen that several calls are attempted during a busy period, the'switches S and S will establish new connection as soon as the old connection is released, the connections being established in the order in which the calling'multiple appears in bank B. There can be no wrong connections, as the switch S does not switch through until switch S has determined the next connection to be established.

If it is desired that certain substations be given answering service only, no key sets need be provided at such substations.

The object and scope of the invention having been described, what is considered to be new and what it is desired to have protected by Letters Patent will be pointed out more fully in the appended claims.

I claim:

1. In a telephone system, a plurality of stations, a link circuit having an automatic switch at each end, lines for said stations multipled in the banks of both of said switches, and means responsive to a call from one of said stations -for causing one of said switches to automatically find the calling line and for causing the other switch to automatically iindthe called line.

2. In a telephone system, a plurality of stations, a link circuit having an automatic switch at each end, lines for said stations multipled in the banks of both of said switches, means responsive to a call from one of said stations for starting an automatic hunting movement by both of said switches,

and test circuits ior causing one switch to stop on the calling line and the other switch onthe called line.

'3. In a telephone system, a plurality of stations, a link circuit having an automatic switch at each end, lines for said stations multipled in the banks of both of said switches, means responslve to a call from one out said stations for starting an auto matic hunting movement by both of said switches, a test circuit for causing one switch to'stop on the calling line, and another test circuit completed responsive to the finding of the calling line for causing the other switch to stop on the called line.

i. In a-telephone system, a plurality of stations, a link circuit having an automatic switch at each end, lines for said stations multipled in the banks of both of said switches, a test contact for each line in the bank of each switch, means responsive to a call from one of said stations for starting an automatic hunting movement by both of said switches and for placing a test potential on the test contact of the calling line in the bank of a first one of said switches, means for stopping such first switch controlled by such test potential, and circuit connections such that when the said first switch stops a test potential is placed upon the test contact of the called-line in the bank oi the other switch to stop such other switch.

5. In a telephone system, a plurality of stations, a link circuit having an automatic switch at each end, lines for said stations multipled in the banks of both of said switches, means responsive to a call from one of said stations for starting an automatic hunting movement by both of said switches, a test relay for each switch, and atest circuit for energizing both relays in series to stop one switch on the calling line and the other switch on the called line.

6. In an int-ercommunicating telephone system, a plurality of stations, a set of keys at each station comprising a key for each oi the other stations, automatic switching mechanism comprising two direct connected switches, lines for said stations multipled in the banks of both of said switches, and circuit arrangements such that the actuation of a key at a calling station will cause one switch to connect with the calling line and the other switch to connect with the station corresponding tothe actuated key.

7 In an intercommunicating telephone system, a plurality of stations, a set of keys at each station comprising a key for each of the other stations, automatic switching mechanism comprising two direct connected switches, lines for said stations inultipled in the banks of both oi? said switches, and circuit arrangements such that the actuation of any key will cause one switch to connect with the line of the station at which the key is located and will cause the other switch to connect with the line of the station which corresponds to the actuated key.

8. In an intercoinmunieating telephone system, a plurality of stations, a set of keys at each station, there being one key for each of the other stations, automatic switching mechanism responsive to the actuation of a key atany calling station to connect the &

calling line with the line of the station called, and circuit arrangements such that upon the restoration of the actuated key at the end of conversation said mechanism will operate automatically to connect the lines corresponding to any other key which may have been actuated before the conversation is finished.

9. In an intercommunicating telephone system, a plurality of stations, a set of keys at each station, there being one key for each of the other stations, automatic switching mechanism responsive to the actuation of a key at any calling station to connect the calling line with the line of the station called, circuit arrangements such that upon the restoration of the actuated key at the end of conversation said mechanism will operate automatically to connect the lines corresponding to any other key which may have been actuated before the conversation is finished, and means for automatically signalling the second calling party to notify him that his connection has been established.

10. In a telephone system, a plurality of stations, a link circuit having an automatic switch at each end, lines for said stations multipled in the banks of both said switches, keys at each station corresponding to the other stations, and circuits closed by the actuation of a key at a calling station for causing one of said switches to connect with the calling line and for causing the other switch to connect with the called line.

11. In a telephone system, a plurality of lines, keys at the station on each line corre- SPOHdlIlg to the stations on the other lines, and two hunting switches responsive to the actuation of a key at a calling station to connect with the calling and called lines, respectively.

12. In a telephone system, a calling and a called line, a link circuit terminating at one end in a hunting switch having access to the calling line and at the other end in a hunting switch having access to the called line, and means at the calling station for causing said switches to start simultaneously and hunt for the calling and called lines, respectively.

In a telephone system, a calling and a called line, a link circuit terminating at one end in a hunting switch having access to the calling line and at the other end in a hunting switch having access to the called line, and means at the calling station for causing said switches to hunt simultaneously for the calling and called lines, respectively.

14. In a telephone system, a calling and a called line, a link circuit terminating at one end in a hunting switch having access to the calling line and at the other end in a hunting switch having access to the called line. means at the calling station for starting the hunting operation of said switches, means at the calling station for closing a test circnit for stopping the first switch on the calling line and for preparing a test circuit for stopping the second switch on the called line, and means in the first switch for closing said second test circuit.

15. In a telephone system, a link circuit for connecting a calling and a called line, an automatic switch at each end of said link circuit, each switch having a test wiper, a test relay in each switch, and circuits for both relays closed at the station on the call ing line, each circuit including the test wiper of the associated switch.

16. In a telephone system, a link circuit for connecting a calling and a called line, an automatic switch at each end of said link circuit, a test relay in each switch, a circuit for one test relay including a wiper of its associated switch only, and a circuit for the other test relay including a wiper in both of said switches.

17. In a telephone system, a link circuit for connecting a calling and called line, an automatic switch at each end of said link circuit, an operating magnet in each switch for operating the same, a test relay in each switch for controlling its operating magnet, and a circuit including said relays in series.

18. In a telephone system, a link circuit for connecting a calling and a called line, an automatic switch at each end of said link circuit, a test relay in each switch, a circuit for the first test relay excluding the second, a circuit for the second test relay including the first, and a test wiper in the second switch included in the said second circuit.

19. In a telephone s et-em, a plurality of lines, automatic selective switching mechanism for connecting with a calling one of said lines, other automatic selective switching mechanism for connecting with a called one of said lines, and a key at the station on the calling line for controlling the operation of all said switching mechanism.

20. In a telephone system, a plurality of lines, automatic selective switching mecha nism for connecting with a calling one of said lines, other automatic selective switching mechanism for connecting with a called one of said lines, and means at the calling station for operating both switching mechanisms simultaneously,

21. In a telephone system, a plurality oi lines, keys at the station on each line corresponding to the stations on the other lines, two hunting switches responsive to the actir ation of a key at a, calling station to connect with the calling and called lines, respec tively, and means responsive to the calling party replacing his receiver without first rcstoring the actuated key for signalling the calling station.

22. In a telephone system, a plurality of stations, a link circuit having an automatic switch at each end, lines for said stations,

and means responsive to a call from one of said stations for causing one of said switches to automatically find and signal the calling line and for causing the other switch to autoinatically find and signal the called line.

23. In a telephone system, a plurality of stations, a link circuit having an automatic switch at each end, lines for said stations, means responsive to a call from one of said stations for causing one of said switches to automatically find and signal the calling line and for causing the other switch to automatically find and signal the called line, and means whereby the first party to answer hears a tone induced by signalling current notifying him that the other party has not answered.

24. In a telephone system, a plurality of lines, a switch for finding the calling line, a second switch for finding the called line. means for operating said switches, and means responsive to said first switch finding the calling line for subsequently stopping said second switch 011 the called line.

25. In a telephone system, a plurality of stations, a set of keys at each station, there being one key for each of the other stations, an automatic switching device responsive to the actuation of a key at any calling station to connect the calling line with the line of the called station, and means responsive to the calling party replacing his receiver with out first restoring the actuated key for signalling the calling station.

26. In an intercommunicating telephone system, a plurality of stations, a set of keys at each station, there being one key for each of the other stations, automatic switching mechanism responsive to the actuation of a key at any calling station to connect the calling line with the line of the station called, circuit arrangements such that upon the restoration of the actuated key at the end of conversation said mechanism will operate automatically to connect the lines corresponding to any other key which may have been actuated before the conversation is finished, and circuit arrangements such that if there is a plurality of keys actuated before conversation is finished said mechanism will operate automatically to connect the lines in a predetermined order.

In witness whereof, I hereunto subscribe my name this th day of March, A. D. 1923.

CLARENCE E. LOMAX. 

